1. Field of the Invention
The present invention relates to elevator doors and, more particularly, to an elevator door system having a header track with a door track mounted on the header track via spring clips for guiding elevator doors.
2. Description of the Related Art
Typical elevators have a two-part door for opening and closing the entrance to the elevator cab. The two-part door includes a “fast” door portion and a “slow” door portion of equal widths. The “fast” door portion, located at the leading edge of the two-leaf door, traverses the entire width of the elevator entrance while the “slow” door portion traverses only about half the width of the elevator opening. Since the “fast” door portion must travel a greater distance, the “fast” door is required to move at a speed greater than that of the “slow” door so that the “fast” door and the “slow” door reach the open and closed positions at the same time.
Prior art elevators utilize two separate header tracks: one for guiding the fast door portion and the other for guiding the slow door portion. The slow door header track may be mounted to the entrance of the elevator cab or to the elevator cab itself; the fast door header track on the other hand is mounted to the slow door header track. Each header track is a formed metal section having a door track or a rail for providing a running surface for a corresponding door roller.
Manufacture of the header tracks often requires multiple tool setups to complete the forming operations. The punching of holes for fasteners requires special tooling loaded onto machines. Field assembly requires numerous operations: mounting of the slow door header track to the entrance, installation of the door, installation of the fast door header track and adjustment of the header tracks and door tracks to obtain proper door clearance. Retaining devices must also be assembled for each door portion, the header track sections, and the door track sections. In short, the existing design requires more parts, special punching and forming to maintain dimensional tolerances as well as numerous hours of field assembly to properly install the two header tracks.
Furthermore, the door track sections are connected via bolt holes on the header plate. Alignment is not always satisfactory and affects horizontal stiffness, thereby allowing deflection and degrading the door rolling performance.
Accordingly there is a need for an elevator door that requires less manufacturing operations and can be more simply installed.